This invention relates generally to the field of drive mechanisms and more particularly to a simplified drive operable for converting a rotary inut motion to an oscillatory output motion in a fabric washing machine where the input and output shafts of the drive mechanism are axially aligned.
Transmissions or drive mechanisms as used in automatic fabric washing machines have, generally speaking, utilized an oscillatory agitator stroke ranging from 170 degrees to 210 degrees with the oscillations per minute ranging from 63 to 100 or 42 to 60 depending upon the speed of the drive motor. It has been found to be advantageous in some situations to provide a drive mechanism which will oscillate the agitator at a generally higher rate of approximately 150 strokes per minute and through a substantially shortened stroke of approximately 90 degrees or less. A drive of this type, when combined with the proper agitator design, provides improved turnover of clothing and corresponding improved washability.
Mechanisms of the type which may be adapted to provide this motion have been used in principle in various drive mechanisms. For example, in U.S. Pat. No. 2,830,457, an automotive windshield wiper drive mechanism is shown in which rotation of a worm causes rotation of a worm gear which, in turn, will rotate an arm or connecting member connected to the worm gear at a point radially displaced from the rotative axis of the gear. As the bearing end of the connecting member rotates, the opposite end will impart an oscillatory movement to the output shaft. The output shaft will be oscillated through an arc of substantially 90 degrees in each revolution of the worm gear. Means are also provided for axially moving the worm gear to change the angle of the connecting arm relative to the worm gear for altering the amplitude of oscillation of the output shaft.
In U.S. Pat. No. 3,400,595 a mechanism is provided for converting rotary to oscillatory motion for use in a testing apparatus such as a viscurometer. A connecting rod between a U-shaped member and the drive member is selectively movable between a series of connecting points to provide for adjustment of the amplitude of oscillation of the output shaft.
In U.S. Pat. No. 4,137,783 a flywheel member is shown which has an eccentrically disposed supporting member. The supporting member mounts one end of a coupling member with the opposite end of the coupling member attached to a shaft perpendicular to the flywheel axis. The supporting member is adjustable within its flywheel mounting location to provide an adjustment for the amplitude of the oscillatory movement.
While numerous applications of mechanisms have been shown which offer conversion of rotary to oscillatory motion and which restrict the oscillatory stroke to generally 90 degrees, each of the disclosed mechanisms teach methods of varying the stroke or otherwise changing the output by moving the connecting member between the input and output shafts. None of these mechanisms teach the use of input and output shafts which are axially aligned for providing a compact drive mechanism which is easily balanced for spinning about a vertical center line.